Implant Deployment Apparatus

ABSTRACT

A delivery system including a restraining member maintains a collapsed implant in its collapsed state for delivery through a small passageway to a desired site in a mammalian body. Once the implant is positioned at the desired site, the restraining member is released so that the stent may expand or be expanded to its expanded state. In a preferred embodiment, the restraining member comprises a sheet of material that surrounds at least a portion of the collapsed stent. Portions of the restraining member are releasably coupled to one another with a low profile thread-like member or suture.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of application Ser. No. 09/985,498,filed Nov. 5, 2001 which is a continuation of application Ser. No.08/772,373, filed Dec. 23, 1996 and now issued as U.S. Pat. No.6,352,561.

BACKGROUND OF THE INVENTION

1. Technical Field

This invention relates generally to implants for repairing ducts andpassageways in the body. More specifically, the invention relates toimplant deployment apparatus.

2. Background Art

Treatment or isolation of vascular aneurysms or of vessel walls whichhave been thickened or thinned by disease has traditionally beenperformed via surgical bypassing with vascular grafts. Shortcomings ofthis procedure include the morbidity and mortality associated withsurgery, long recovery times after surgery, and the high incidence ofrepeat intervention needed due to limitations of the graft or of theprocedure.

Vessels thickened by disease may be treated less invasively with stentswhich mechanically hold vessels open. In some instances, stents may beused subsequent to or as an adjunct to a balloon angioplasty procedure.Stents also have been described in conjunction with grafts where thegraft is intended to provide a generally smooth interface with bloodflowing through the vessel.

Generally, it is important that the stent or stent-graft be accuratelydeployed so that it may be positioned at the desired location.Endovascular stent or stent-graft deployment can be summarized as atwo-step process. The first step is moving the stent within thevasculature to a desired location. The stent or stent-graft may beself-expanding or balloon expandable. In both cases, the implant istypically delivered in a collapsed state to facilitate delivery throughrelatively small vessel lumens. The second step involves some method of“locking” the stent or stent-graft into its final geometry so that itwill remain implanted in the desired location.

A number of techniques for delivering self-expanding or balloonexpandable stents and stent-grafts are known. In the case of aself-expanding stent or stent-graft, a restraining mechanism typicallyis used to keep the stent or stent-graft in its collapsed state duringdelivery. The restraining mechanism is later removed to allow the stentor stent-graft to expand and engage the vessel wall at the desiredimplantation site. In the case of a balloon expandable stent orstent-graft, a restraining mechanism typically keeps the expandabledevice in a collapsed position during delivery with an inflatableballoon positioned within the collapsed device. The restrainingmechanism is later removed to allow for inflation of the balloon whichcauses the stent or stent-graft to expand so that it engages the vesselwall. Generally, tubular sheaths or tying elements, which may be in theform of a filament or thread, have been described to restrain thecollapsed devices.

U.S. Pat. No. 4,878,906, to Lindemann et al., discloses balloonexpandable stent-grafts which are deployed through a tubular sheath. Thestent grafts are forwarded in a collapsed state along the vessel untilthey are in the correct location where the sheath is withdrawn, allowingexpansion of the balloon within the stent-graft. After the balloon hasexpanded the stent-graft into final position, the balloon is deflatedand drawn back into the tubular sheath. An alternative deployment methoddisclosed Lindemann et al. dispenses with the tubular sheath and uses a“thread” wrapped around the stent-graft and balloon which can bewithdrawn when balloon inflation is desired.

Pinchuk, U.S. Pat. No. 5,019,090, shows a helically wrapped spring stentwhich is deployed with a balloon expansion catheter through a “sheath”which holds the stent and balloon catheter in a generally compressedstate. Once the stent and balloon have been forwarded into the correctposition along a lumen, the sheath is withdrawn. The balloon is theninflated, deflated, and withdrawn, leaving the stent in finalimplantation position.

U.S. Pat. No. 5,246,452, to Sinnott, discloses a porous vascular graftwhich is implanted with a tear-away removable nonporous sheath. Once thegraft has been forwarded into the desired position, circulation isrestored to the area and blood is allowed to clot inside of the porousgraft. After five minutes of clotting, the nonporous sheath can beremoved by cutting or by pulling a string which tears the sheath andpulls it away.

U.S. Pat. No. 5,344,426, to Lau et al., discloses an expandable stentwhich is preferably self locking when expanded. The stent is positionedover an expandable member such as a balloon catheter and covered by aone or two layer sheath which is connected to a guidewire. When theassembly of sheath, stent, and expandable member has been forwarded tothe desired position, the sheath is removed by moving the guidewiredistally. With the sheath pulled off of the stent, the expandable membercan be activated to expand the stent into its final position.

U.S. Pat. No. 5,366,473, to Winston et al., discloses an assembly inwhich a vascular graft is held in a compressed state over a pair ofstents by a sheath. The stents take the form of flexible sheets woundaround a spool. After the spool has been inserted to the correctendovascular site, the sheath is withdrawn allowing the stents to unwindand press the graft against the vessel walls.

Strecker, U.S. Pat. No. 5,405,378, discloses an expandable prosthesiswhich is held in radially compressed condition by a releasable sheath.The sheath can be a strippable meshwork which allows the compressedprosthesis to expand when the meshwork is controllably unraveled.

Generally, the mechanisms described above involve a number of componentsthat may increase operational complexity. In addition, the size andmechanical properties of these mechanisms may limit deliverability ofimplants in small vessels. Delivery accuracy also may be a problem asdiscussed.

The diameter of conventional telescoping stent sheaths may contribute toundesirable friction with the delivery catheter as the sheath is pulledfrom the stent and over a push rod during deployment. This may makedeployment accuracy difficult to control. Push rods, which are used topush the stent through the delivery catheter and which typically have alength of up to about 100 cm, also may contribute to undesirablefriction with the catheter. This problem may be exacerbated where thecatheter bends along its path in the vasculature. The sheath may alsoreposition the stent as it is retracted.

SUMMARY OF THE INVENTION

The present invention generally involves a delivery system for animplant, such as a stent or stent-graft. The delivery system generallycomprises a sheet of material adapted to extend around at least aportion of a collapsed implant, such as a collapsed stent orstent-graft. The sheet of material may form a tubular member whenextending around at least a portion of a collapsed member. The systemalso may include a coupling member for coupling portions of the sheettogether to maintain the implant in its collapsed state during deliveryto a desired site in a mammalian body. With this construction a smoothinterface between the collapsed stent and a vessel lumen, as compared tothread-like restraining members, may be achieved.

According to another aspect of the invention, the sheet may beconstructed of a thin material which does not significantly contributeto the structural rigidity or cross-sectional profile to the deliveryassembly. This construction may also eliminate the need for externalsheathing or a guide catheter and is believed to advantageously increasethe ability of the surgeon to deliver the device to relatively remotesites and through small tortuous vasculature. In addition, the sheet maycomprise implantable material so that after release it may remain withthe stent at the desired site.

According to another embodiment of the invention, an assembly comprisinga stent and a restraining member coupled to the stent is provided. Thestent has a collapsed and an expanded state and the restraining membercomprises a sheet of material adapted to be wrapped around at least aportion of the stent when the stent is in the collapsed state. Portionsof the sheet are adapted for coupling to one another to maintain thesheet wrapped around at least or portion of the stent in its collapsedstate. Thus, in one configuration, portions of the sheet are releasablycoupled to one another so that the sheet maintains the stent in itscollapsed state.

According to another aspect of the invention, the portions of the sheetthat may be coupled to one another may be coupled with a filament orthread-like member. The stent may be expanded (or allowed to expand whena self-expanding stent is used) after the thread-like coupling member isremoved such as by being remotely pulled by a pull line, which may be anextension of the coupling member. Since the pull line may also have athread-like low profile, friction between with the catheter, throughwhich the pull line is pulled, and the pull line is minimized. It isbelieved that such construction may further facilitate deploymentaccuracy.

According to another aspect of the invention, multiple restrainingmembers may be used. Alternatively, multiple coupling members may beused to couple multiple portions of one of more restraining members.These constructions can reduce deployment time and may reduce the timein which fluid flow may disturb the position of the implant as it isdeployed.

According to another aspect of the invention an assembly comprises astent and a restraining member coupled to the stent. The stent has acollapsed and an expanded state and first and second portions that moverelative to one another when said stent moves between its collapsed andexpanded states. The said restraining member comprises a sheet ofmaterial adapted to be wrapped around at least a portion of the stentwhen it is in its collapsed state, and portions of the sheet beingadapted for coupling to one another to maintain said sheet wrappedaround at least a portion of the stent in its collapsed state. The saidassembly further includes a member having a first portion coupled to therestraining member and a second portion coupled to one of the stentfirst and second portions.

According to another aspect of the invention, an expandable stent, whichis restrained in a collapsed state with a restraining member, isreleased and the restraining member urged against the wall of the lumenin which the stent is placed. Since the restraining member remains atthe site, the number of deployment steps can be reduced as compared toother techniques (e.g. pushing a self-expanding implant out the end of aradially constraining sheath and retracting the sheath).

According to another aspect of the invention, a method of preparing astent for delivery comprises restraining a collapsed stent in a sheet ofmaterial which may be in the form of a tube and coupling side margins ofthe tube.

According to another aspect of the invention, an expandable stent (orstent-graft) is collapsed into a generally cylindrical or tubularrestraining by pulling the stent through a tapered member and into atubular restraining member.

The above is a brief description of some deficiencies in the prior artand advantages of the present invention. Other features, advantages, andembodiments of the invention will be apparent to those skilled in theart from the following description, accompanying drawings, and appendedclaims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a mammalian implant that is restrainedin a collapsed state in accordance with the principles of thisinvention.

FIG. 2 is an end view of the restrained implant of FIG. 1.

FIG. 3 is a perspective view of the assembly of FIG. 1 with therestraint released and the implant in an expanded state.

FIG. 4A is an end view of the assembly of FIG. 3.

FIG. 4B is a bottom plan view of the restraining member of FIG. 4A.

FIG. 5A shows a restraining member retraction mechanism according toanother embodiment of the invention where the mechanism is in anunactuated state.

FIG. 5B shows the mechanism of FIG. 5A in an actuated state.

FIG. 5C shows a restraining member retraction mechanism according to yetanother embodiment of the invention where the mechanism is in anunactuated state.

FIG. 5D shows the mechanism of FIG. 5C in an actuated state.

FIG. 6A is a perspective view of another embodiment of the implant inconjunction with the restraining member of FIG. 1.

FIG. 6B is a perspective view of a further embodiment of the implant inconjunction with the restraining member of FIG. 1.

FIG. 7A illustrates the restraining and coupling member of FIG. 1 andthe pull direction for removing the coupling member from the restrainingmember.

FIG. 7B shows the assembly of FIG. 7A with the coupling member loosenedto illustrate the chain knots used according to one embodiment of theinvention.

FIG. 7C diagrammatically represents release of the assembly of FIG. 7Aor 7B as the coupling member is pulled in the direction shown.

FIGS. 8A, 8B, 8C, 8D, 8E, and 8F diagrammatically show a procedure forloading an expandable stent-graft into a restraining member inaccordance with the present invention prior to endolumenal delivery.

FIG. 9A diagrammatically shows delivering a restrained implant to adesired site in a mammalian body lumen in accordance with the presentinvention with the coupling member configured as shown in FIGS. 7A-7C.

FIG. 9B is a sectional view of FIG. 9A taken along line 9B-9B.

FIG. 9C shows an alternate multiple restraining member arrangement forthat shown in FIG. 9A.

FIG. 10A diagrammatically shows partial deployment of the implantassembly illustrated in FIG. 9A showing progressive expansion in adirection away from the distal end of the illustrated guidewire (i.e.,toward the illustrated hub).

FIG. 10B is a sectional view of FIG. 10A taken along line 10B-10B.

FIG. 11A diagrammatically shows full deployment of the implant assemblyillustrated in FIG. 9A. FIG. 11B shows a cross sectional view.

FIGS. 12A, 12B, 12C, and 12D diagrammatically show deployment of arestrained implant according to another embodiment of the inventionwhere the coupling member configuration provides release from the middleportion of the implant outward toward the implant ends.

FIG. 13 illustrates one coupling member configuration for deployment asshown in FIGS. 12A-12D.

FIG. 14A is a perspective view of a bifurcated stent-graft that can beused with the illustrated delivery systems.

FIG. 14B is a top plan view of the bifurcated stent-graft of FIG. 14A.

FIG. 14C is a cross-section view taken along section line 14C-14Cdepicted in FIG. 14A.

FIG. 14D is a cross-sectional view taken along section line 14D-14Ddepicted in FIG. 14A showing an alternate embodiment.

FIG. 15 is a front view of the assembled bifurcated stent-graft of FIG.14A placed at a bifurcation site within the vasculature of a body.

FIG. 16 is a perspective break-away view showing a close-up of oneconstruction of stent anchoring apexes.

FIG. 17 is a perspective break-away view showing a close-up of apreferred construction of the stent anchoring apexes.

FIG. 18 is a cross-sectional view of the stent-graft of FIG. 14B takenalong section line 18-18.

FIG. 19 is a cross-sectional view of the stent-graft of FIG. 14A takenalong section line 19-19.

FIG. 20 is an enlarged partial cross-sectional view of the contralateralleg connection depicted in FIG. 19.

FIG. 21 and FIG. 22 are enlarged partial cross-sectional views ofalternative constructions of the receiving lumen.

FIG. 23 is a partial perspective view of an alternate scallopedconstruction of the proximal region of the contralateral leg component.

FIGS. 24A and 24B are cross-sectional views taken along section line24A-24A as shown in FIG. 14A depicting a free state and a forced staterespectively.

FIGS. 25A and 25B are cross-sectional views taken along section line25A-25A as shown in FIG. 23 depicting a free state and a forced staterespectively.

FIG. 26A is a front view of preassembled graft components.

FIGS. 26B and 26C are respectively the front view and top view of theassembled graft of FIG. 26A.

FIG. 27A is a front view of the unassembled components of an alternateconstruction of the graft element.

FIG. 27B is a front view of the assembled graft element according to thealternative construction of FIG. 27A.

FIGS. 28A through 28E diagrammatically show deployment of a bifurcatedstent-graft.

FIGS. 29A, 29B, 29C, and 29D diagrammatically show deployment of abifurcated stent-graft using an alternate delivery system.

DETAILED DESCRIPTION

Referring to the drawings in detail wherein like numerals indicate likeelements, delivery systems for delivering implants or devices, such asstents or stent-grafts, to a desired site in mammalian vasculature areshown in accordance with the principles of the present invention. Thedelivery systems of the present invention generally include arestraining member that is adapted and configured for surrounding atleast a portion of a collapsed or compressed implant and a couplingmember(s) for releasably coupling portions of the restraining member toone another to maintain the implant in its collapsed or compressedstate.

Referring to FIGS. 1-4, an implant delivery system constructed inaccordance with the present invention is shown. Delivery system (100),generally includes a restraining member (102), which as shown may be inthe form of a sheet of material, and a coupling member (104) forreleasably coupling portions of the restraining member to one another.The restraining member portions that are coupled may differ than thoseillustrated, but preferably are selected to maintain the implant, suchas self-expanding stent-graft (106), in a collapsed or compressed stateas shown in FIGS. 1 and 2 where the restraining member (102) is shown inthe form of a tube. In the illustrative embodiment, the coupling member(104) is shown as a filament or thread-like element which prevents therestraining member (102) from rearranging to a configuration where thestent-graft (106) could expand to its expanded state.

The implant may be collapsed in any suitable manner for placement withinthe restraining member (102). For example, the implant may be folded orradially crushed before placement within the restraining member (102) aswill be described in more detail below. As shown in FIGS. 9-11, adelivery assembly (108), which includes the restraining member (102) andthe stent-graft (106), has relatively small cross-sectional dimensionswhich facilitate endoluminal delivery of the assembly to a site wherethe natural lumen diameter may be smaller than the expanded diameter ofthe stent-graft (106).

Referring to FIGS. 3 and 4A, the assembly (108) is shown in a deployedstate after removal of the coupling member (104). The restraining member(102) may be fixedly secured to the stent-graft (106) so that the twocomponents remain attached after expansion at the desired deploymentsite. The attachment between the restraining member and the implantpreferably is made to prevent significant movement between therestraining member and stent-graft after deployment which could disruptendovascular fluid flow. Referring to FIGS. 4A and 4B multiple sutures(110) may be used to fixedly attach the restraining member (102) to thestent-graft (106). More specifically, the sutures can form loops thatpass through the restraining member and around portions of the stent asshown in FIG. 4A. It is further noted that although one arrangement ofthe sutures (110) is shown in FIG. 4B other arrangements may be used.

Although other configurations of the restraining member (102) can beused, a preferred configuration is a generally rectangular one havingconstant width as shown in FIG. 4B. For example, in the case where therestraining member is used in conjunction with a modular bifurcatedstent as will be described below, the restraining member may have asimilar rectangular configuration as that shown in FIG. 4B.Alternatively, it may have two differently sized rectangular portionsarranged to mate with the regions of different diameter (trunk and leg)or another configuration that would maintain the implant in a collapsedstent when secured. Returning to FIG. 4B, the restraining member may bedescribed as having side margins (112) that extend between the ends(114) of the member. Eyelets (116) are disposed along the side marginsso that the coupling member (104) may be laced or threaded therethrough.The eyelets may be in the form of through holes (118), which may beformed by a uniform-diameter puncturing device or by other means such aslaser-drilling. Alternatively, the eyelets may be formed by loops (120)which may be attached to the side margins (112) or formed by other meansas would be apparent to one of ordinary skill in the art.

It is further desirable to have structural reinforcement at the sidemargins (112) to minimize or eliminate the possibility of the couplingmember (104) from tearing the restraining member (102) when under load.Reinforced side margins may be formed by folding a portion of therestraining member (102) over a reinforcement member (122), such as asmall diameter suture, which may be heat bonded between the two layersof sheet material. With this construction, a relatively low profile beadof material along the side margins (112) prevents or minimizes thepossibility of tear propagation and, thus, accidental uncoupling of therestraining member (102). The small diameter suture (122) may compriseePTFE, for example.

As the restraining member (102) constrains a collapsed self-expandingstent-graft, for example, forces resulting from stored spring energy inthe collapsed stent-graft (106) will be acting on the restraining member(102) when it is configured for delivery. Thus, according to anotheraspect of the invention the restraining member (102) may comprise amaterial which is creep resistant and can withstand required loadswithout stretching over time. The restraining member (102) may comprise,for example, ePTFE, which is believed to provide suitable creepresistance, flexibility, and biocompatibility in a thin sheet form whichcan be heat bonded. Other materials also may be used includingpolyethers such as polyethylene terephthalate (DACRON® or MYLAR®) orpolyaramids such as KEVLAR®.

The thread-like coupling member (104) may also comprise ePTFE. Suturesof polyethers such as polyethylene terephthalate (DACRON® or MYLAR®) orpolyaramids such as KEVLAR® or metal wire comprising nitinol, stainlesssteel or gold may also be used for the coupling member (104). Thecoupling member (104) may simply extend to form a remote pull line aswill be discussed below. Alternatively, a metallic pull line, such asone comprising stainless steel may be coupled to a nonmetallic couplingmember (104) such as one comprising ePTFE. The coupling may be made byfolding the end of the metallic pull line back upon itself to form aneyelet and threading the coupling member therethrough and securing it tothe eyelet with a knot.

It is further noted that the width of the restraining member, when in aflat orientation as shown in FIG. 4A, preferably is less than thediameter of the implant. Typically the restraining member width will beless than about 40 mm (typically about 25-40 mm when the device is sizedfor thoracic aorta applications), and typically less than about 15 mm inother applications where the lumen is smaller. The sheet of materialpreferably has a thickness less than 0.010 inch (0.254 mm) and morepreferably less than 0.005 inch (0.127 mm). In addition, the length ofthe restraining member preferably is less than or equal to that of theimplant.

According to the present invention, a retraction assembly may beprovided to retract the restraining member during expansion of theimplant, so that the length of the restraining member is maintained tobe about equal to or less than that of the implant. The expandableportion of the implant may undergo minor amounts of shortening along theaxial direction due to the expansion thereof in the radial direction,which may lead to an overlap of the restraining member at the ends ofthe implant, but for the use of some type of retraction assembly inthese situations. The retraction assembly minimizes or eliminates therisk of the restraining member extending beyond the implant andinterfering with any channel formed by the implant, or any fluid flowingtherethrough after expansion.

Referring to FIGS. 5A-5D, retraction assemblies or mechanismsconstructed according to the principles of the invention are shown. InFIG. 5A, a retraction assembly (340) is shown including a biocompatiblefilament (342), which includes a portion that is stitched, tied orotherwise fixed to the restraining member (102), as shown at anattachment point (348), adjacent to one end of the restraining member.Filament (342) is passed underneath the members forming the first or endhelical turn of the stent (126) and looped under or otherwise slidablysecured to a portion of the second, third or another helical turn otherthan the first helical turn such a an apex or bend portion (344) in asecond turn. The other end portion of filament (342) is further fixed,by tying or other means, to a portion of the stent that iscircumferentially spaced from the attachment point (348) or the apex orbend portion (344), for example, such as an apex or bend portion (346)of the same helical turn. Preferably, the filament (342) is loopedthrough an apex portion (344) of the second helical turn and tied to anapex portion (346) which is adjacent to the apex portion (344) as shownin FIG. 5A.

FIG. 5A shows the stent in the compressed state. Upon expansion of thestent, as mentioned above, the members of the stent expand to effect theradial expansion of the stent, as shown in FIG. 5B. Because the distancebetween apex portions (344) and (346) becomes greater upon expansion ofthe stent, and because the filament (342) is relatively unyieldable andinelastic, the distance between the attachment point (344) and the apexportion (348) necessarily decreases. The result is that the end of therestraining member (102) is retracted with respect to the stent (126),as shown in FIG. 5B. Thus, the retraction along the longitudinal axis ofthe restraining member is driven by the expanding distance betweenadjacent apexes in this embodiment. Although only one retractionmechanism is shown at one end of the restraining member, anothersimilarly configured and arranged retraction mechanism may be used atthe other end of the restraining member.

FIGS. 5C and 5D show another embodiment for a retraction assembly. Theviews of this assembly (as are those shown in FIGS. 5A and 5B) are takenfrom a location between the generally cylindrical graft and stentlooking radially outward. In contrast to that shown above where one endportion of a filament is secured to the restraining member and anotherto a portion of the stent that circumferentially moves during stentexpansion, the other end of the filament is secured to a portion of astent that moves generally parallel to the longitudinal axis of thestent (axially) as the stent expands. In this embodiment, at least oneapex portion (364) of an end helix of the stent member (126′) (whichdiffers from stent (126) in that it includes eyelets or loops which maybe formed as shown in the drawings) is made shorter than the majority ofapex portions (366). However, the apex portions may be otherwiseconfigured such as those shown in FIGS. 4A and 4B. A filament (362) istied or otherwise fixed at one end to apex portion (364), and at theother end, to one end portion of the restraining member (102). As shownin FIG. 5D, upon radial expansion of the stent, inwardly positioned apexportion (364) retracts to a greater extent in the longitudinal or axialdirection than the full height apex portions (366) which are shown inthe last or most outwardly positioned turn of the stent. This relativegreater retraction directly translates through filament (362) such thatthe end of the restraining member (102) is retracted relative to apexportions (366). As described above, another similarly constructedretraction mechanism may be provided at the other end of the restrainingmember.

Returning to FIG. 1, one stent-graft construction that may be used inconjunction with the delivery systems disclosed herein is shown.Stent-graft (106) generally includes a thin-walled tube or graft member(124), a stent member (126), which can be a self-expanding stent, and aribbon or tape member (128) for coupling the stent (126) and graft (124)members together. The stent (126) and graft (124) members may be heatbonded together, thus sealing in portions of the stent member (126) thatare between the tape member (128) and the graft member (124). Themechanical properties of the stent-graft (128) may be customized, forexample, through materials selection, by varying the structural patternof the stent member, varying the thickness of the tape (128) and graft(124) members, and varying the pattern with which the tape membercontacts the stent and graft members.

As shown in FIG. 1A, the tape member (128) may cover only a portion ofthe stent member (126) as it follows the helical turns of the undulatingstent member. With this construction, regions of the stent member do notinterface with the tape member when the stent-graft is in anuncompressed state, for example. This is believed to advantageouslyreduce shear stresses between the stent member (126) and the tape member(128) when the stent-graft undergoes bending or compression, therebyreducing the risk of tearing the graft (124) or tape (128) members orcausing delamination between the stent (126) and graft (124) members.

The tape member (128) also preferably has a generally broad or flatsurface for interfacing with the stent (126) and graft (124) members ascompared to filament or thread-like structures such as sutures. Thisincreases potential bonding surface area between the tape member (128)and the graft member (124) to enhance the structural integrity of thestent-graft. The increased bonding surface area also facilitatesminimizing the thickness of the tape member (128). It has been foundthat a tape member in the form of a generally flat ribbon as shown inthe drawings provides desired results.

Tape members having widths of 0.025, 0.050 and 0.075 inches applied to astent member having a peak-to-peak undulation amplitude of about 0.075inch are believed to provide suitable results. However, it has beenfound that as the tape member band width increases, the stent-graftflexibility generally is diminished. It is believed that a tape memberwidth of about one-fourth to three-fourths the amplitude of the stentmember undulations, measured peak-to-peak, may be preferred (may be morepreferably about one-third to two-thirds that amplitude) to optimizeflexibility. It also has been found that by positioning one of thelateral margins of the tape member adjacent to the apexes, the tapemember width may be reduced without significantly sacrificing apexsecurement. Varying the width of the tape member (e.g., varying width ofthe tape along the length of the stent graft) can also result in theadjustment of other structural properties. Increasing the width can alsopotentially increase the radial stiffness and the burst pressure anddecrease the porosity of the device. Increasing band width can alsodiminish graft member wrinkling between coupling member turns.

The tape member (or separate pieces thereof) also may surround theterminal end portions of the stent-graft to secure the terminal portionsof the graft member to the stent member.

FIGS. 6A and 6B illustrate further stent-graft constructions that may beused with the delivery systems described herein. Referring to FIG. 6A,stent-graft (200) is the same as stent-graft (106) with the exceptionthat stent-graft (200) includes a filament that couples stentundulations in adjacent turns. Filament (202) is laced or interwovenbetween undulations of the stent member and acquires a helicalconfiguration (i.e., it forms a secondary helix) in being laced as such.Such a configuration is disclosed in PCT publication No. WO 95/26695(International Application No. PCT/US95/04000) the entirety of which ishereby incorporated herein by reference. The stent-graft (300) shown inFIG. 6B is the same as that shown in FIG. 6A with the exception that thefilament (302) is interwoven between undulations in the same helicalturn of the stent member.

The filaments (202, 302) are of the same construction and may be of anyappropriate filamentary material which is blood compatible orbiocompatible and sufficiently flexible to allow the stent to flex andnot deform the stent upon folding. Although the linkage may be a singleor multiple strand wire (platinum, platinum/tungsten, gold, palladium,tantalum, stainless steel, etc.), much preferred is the use of polymericbiocompatible filaments. The flexible link may be tied-off at either endof the stent-graft (100), for example, by wrapping its end portionaround the stent and tying it off at the point at the beginning of thelast turn as would be apparent to one of ordinary skill.

A percutaneously delivered stent-graft must expand from a reduceddiameter, necessary for delivery, to a larger deployed diameter. Thediameters of these devices obviously vary with the size of the bodylumen into which they are placed. For instance, the stents of thisinvention may range in size from 2.0 mm in diameter (for neurologicalapplications) to 40 mm in diameter (for placement in the aorta). A rangeof about 2.0 mm to 6.5 mm (perhaps to 10.0 mm) is believed to bedesirable. Typically, expansion ratios of 2:1 or more are required.These stents are capable of expansion ratios of up to 5:1 for largerdiameter stents. Typical expansion ratios for use with the stents-graftsof the invention typically are in the range of about 2:1 to about 4:1although the invention is not so limited. The thickness of the stentmaterials obviously varies with the size (or diameter) of the stent andthe ultimate required yield strength of the folded stent. These valuesare further dependent upon the selected materials of construction. Wireused in these variations is typically of stronger alloys, e.g., nitinoland stronger spring stainless steels, and have diameters of about 0.002inches to 0.005 inches. For the larger stents, the appropriate diameterfor the stent wire may be somewhat larger, e.g., 0.005 to 0.020 inches.For flat stock metallic stents, thicknesses of about 0.002 inches to0.005 inches is usually sufficient. For the larger stents, theappropriate thickness for the stent flat stock may be somewhat thicker,e.g., 0.005 to 0.020 inches.

The following example is provided for purposes of illustrating apreferred method of manufacturing a stent-graft as shown in FIG. 3. Itshould be noted, however, that this example is not intended to limit theinvention. The stent member wire is helically wound around a mandrelhaving pins positioned thereon so that the helical structure andundulations can be formed simultaneously. While still on the mandrel,the stent member is heated to about 460° F. for about 20 minutes so thatit retains its shape. Wire sizes and materials may vary widely dependingon the application. The following is an example construction for astent-graft designed to accommodate a 6 mm diameter vessel lumen. Thestent member comprises a nitinol wire (50.8 atomic % Ni) having adiameter of about 0.007 inch. In this example case, the wire is formedto have sinusoidal undulations, each having an amplitude measuredpeak-to-peak of about 0.100 inch and the helix is formed with a pitch ofabout 10 windings per inch. The inner diameter of the helix (whenunconstrained) is about 6.8 mm. (The filament when used as shown inFIGS. 6A and 6B may have a diameter of about 0.006 inch.)

In this example, the graft member is porous expandedpolytetrafluorethylene (PTFE), while the tape member is expanded PTFEcoated with FEP. The tape member is in the form of a flat ribbon (asshown in the illustrative embodiments) that is positioned around thestent and graft member as shown in FIG. 3. The side of the tape memberor ribbon that is FEP coated faces the graft member to secure it to thegraft member. The intermediate stent-graft construction is heated toallow the materials of the tape and graft member to merge and self-bindas will be described in more detail below.

The FEP-coated porous expanded PTFE film used to form the tape memberpreferably is made by a process which comprises the steps of:

(a) contacting a porous PTFE film with another layer which is preferablya film of FEP or alternatively of another thermoplastic polymer;

(b) heating the composition obtained in step (a) to a temperature abovethe melting point of the thermoplastic polymer;

(c) stretching the heated composition of step (b) while maintaining thetemperature above the melting point of the thermoplastic polymer; and

(d) cooling the product of step (c).

In addition to FEP, other thermoplastic polymers including thermoplasticfluoropolymers may also be used to make this coated film. The adhesivecoating on the porous expanded PTFE film may be either continuous(non-porous) or discontinuous (porous) depending primarily on the amountand rate of stretching, the temperature during stretching, and thethickness of the adhesive prior to stretching.

In constructing this example, the thin wall expanded PTFE graft was ofabout 0.1 mm (0.004 in) thickness and had a density of about 0.5 g/cc.The microstructure of the porous expanded PTFE contained fibrils ofabout 25 micron length. A 3 cm length of this graft material was placedon a mandrel the same diameter as the inner diameter of the graft. Thenitinol stent member having about a 3 cm length was then carefullyfitted over the center of the thin wall graft.

The stent-member was then provided with a tape coupling member comprisedof the FEP coated film as described above. The tape member was helicallywrapped around the exterior surface of the stent-member as shown in FIG.3. The tape member was oriented so that its FEP-coated side faced inwardand contacted the exterior surface of the stent-member. This tapesurface was exposed to the outward facing surface of the thin wall graftmember exposed through the openings in the stent member. Theuniaxially-oriented fibrils of the microstructure of thehelically-wrapped ribbon were helically-oriented about the exteriorstent surface.

The mandrel assembly was placed into an oven set at 315° C. for a periodof 15 minutes after which the film-wrapped mandrel was removed from theoven and allowed to cool. Following cooling to approximately ambienttemperature, the mandrel was removed from the resultant stent-graft. Theamount of heat applied was adequate to melt the FEP-coating on theporous expanded PTFE film and thereby cause the graft and couplingmembers to adhere to each other. Thus, the graft member was adhesivelybonded to the inner surface of the helically-wrapped tape member throughthe openings between the adjacent wires of the stent member. Thecombined thickness of the luminal and exterior coverings (graft and tapemembers) and the stent member was about 0.4 mm.

Although the invention has been described with reference to thestent-graft examples illustrated in the drawings, it should beunderstood that it can be used in conjunction with other devices, stentsor stent-grafts having constructions different than those shown. Forexample, delivery systems described herein may be used in conjunctionwith bifurcated stents or stent-grafts as will be described in detailbelow. In addition, although a self-expanding stent-graft has beendescribed, balloon expanding stent-grafts also may be used inconjunction with the delivery systems described herein. Thesestent-grafts require a balloon to expand them into their expanded stateas opposed to the spring energy stored in a collapsed self-expandingstent.

Referring to FIGS. 7A-C, one slip knot configuration that may be used inconjunction with the thread-like coupling member (104) will bedescribed. The restraining member (102) is shown without an implantpositioned therein for purposes of simplification. FIG. 7A illustratesthe slip knot in a prerelease or predeployment state. The series ofknots are generally flush with the restraining member (102) surface andadd very little profile to the construct which is preferred duringimplant delivery. FIG. 7B shows the assembly of FIG. 7A with thethread-like coupling member (104) loosened to illustrate how the chainknots (130) may be formed. FIG. 7C diagrammatically represents releaseof the assembly of FIG. 7A or 7B. The illustrated stitch is releasableby pulling one end of the line that results in releasing of thecylindrical or tubular restraining member and then deployment of thedevice. This particular stitch is called a chain stitch and may becreated with a single needle and a single line. A chain stitch is aseries of loops or slip knots that are looped through one another suchthat one slip knot prevents the next slip knot from releasing. When theline is pulled to release a slip knot, the following slip knot is thenreleased and that releases the next slip knot. This process continuesduring pulling of the line until the entire line is pulled out of therestraining member.

Referring to FIGS. 7A-C, as the unknotted portion or the lead (132) ofthe thread-like coupling member (104) is pulled, such as in thedirection shown by reference arrow (134), each consecutive chain knot(132) releases the next adjacent one. In the preferred embodiment, thechain knots (130) of the coupling member (104) are arranged toprogressively release the collapsed implant in a direction away from thedistal portion of the delivery catheter as shown in FIG. 10A and as willbe discussed in detail below.

Referring to FIGS. 8A through 8F, a method for making an assemblycomprising a restraining member with a collapsed or compressed implanttherein is shown for purposes of example. FIG. 8A shows the restrainingmember (102) with its side margins releasably coupled to one another andits left end dilated by a tapered mechanical dilator (402). A smallfunnel (404) is then inserted into the restraining member (102) as shownin FIGS. 8B and 8C. The small funnel (404) and restraining member (102)are then mounted onto a pulling frame (410), and a large funnel (406) isfitted into the small funnel (404) as shown in FIG. 8D. Traction or pulllines (408), which have been sutured to one end of the stent-graft,(106) are pulled through the large funnel (406), small funnel (404), andrestraining member (102) with a tapered mandrel (416). As shown in FIG.8F, the pull lines (408) are fastened to a tie down post (412) locatedon a tension screw (414) and then are pulled by the tension screw (414).The stent-graft (106) is then pulled and collapsed sequentially throughthe large (406) and small (404) funnels, and then into the restrainingmember (102). Once the stent-graft (106) has been radially collapsedinto the restraining member (102), which has its side margins coupledtogether, the pull lines (408) can be removed. The mandrel (416) may beinserted into the restrained implant to facilitate introduction ofanother component. In the preferred embodiment, a multilumen catheter(136) (FIGS. 9-11) is introduced through the center of the compressedstent-graft (106) and is used to deliver the radially restrainedstent-graft to the desired endolumenal site.

It also is noted that the funnels may be chilled to facilitatecompression of the stent when the stent is made of nitinol. That is,when the stent is made of nitinol, the funnels may be chilled below 0°C. or below the transition temperature (M_(f)) where nitinol is in itsmartensitic state. In addition, the stent-graft could be folded firstand then reduced in profile by pulling through the funnel and into therestraining member. Cooling may be accomplished by spray soaking thestentgraft with chilled gas such as tetrafluroethane. Micro-Dust™ drycircuit duster manufactured by MicroCare Corporation (Conn) providessuitable results. The spray canister preferably is held upside down todischarge the fluid as a liquid onto the stent-graft.

A method of deploying an implant will be described with reference toFIGS. 9-11. In general, an implant may be delivered percutaneously withthe delivery systems described herein, typically through thevasculature, after having been assembled in the reduced diameter form(see e.g. FIG. 1). At the desired delivery site, the implant may bereleased from the restraining member, thus allowing the implant toexpand or be expanded against the lumen wall at the delivery site.Although other devices including stents or stent-grafts may be used,such as balloon expandable stents, the following example will be madewith reference to a self-expanding stent-graft, which has the ability tofully expand itself into its final predetermined geometry whenunconstrained. More particularly, the following example will be madeusing a delivery system as shown in FIGS. 1 and 7A-C and a stent-graftconstruction as shown in FIG. 3.

Referring to FIGS. 9A and 9B, an implant delivery assembly including acollapsed stent-graft (106) that is confined within a restraining member(102) and, which surrounds a distal portion of the delivery catheter(136), is shown. The attending physician will select a device having anappropriate size. Typically, the stent-graft will be selected to have anexpanded diameter of up to about 20% greater than the diameter of thelumen at the desired deployment site.

The delivery catheter preferably is a multilumen catheter. The proximalportion of the catheter (136) is coupled to a hub (140), which includesa guidewire port (142) for a guidewire (142), and a deployment knob(144), which is coupled to the lead (132) of the thread-like couplingmember (104). Accordingly, when the knob (144) is retracted, therestraining member (102) is released so that the stent-graft may expand.The hub (140) also may include a flushing port (146) as is conventionalin the art. The stent-graft (106) is held axially in place prior todeployment by a proximal barrier (148) and distal barrier (150) whichare positioned around delivery catheter (136) adjacent to the proximaland distal portions, respectively, of the restrained stent-graft. Theproximal and distal barriers (148, 150) may be fixedly secured to themultilumen catheter (136) to restrict any axial movement of therestrained stent-graft. The barriers preferably are positioned to abutagainst the stent-graft or restraining member. The lead (132) of thecoupling member (104) is passed through an aperture (152) in theproximal barrier (148) which is fluidly coupled to a lumen in thedelivery catheter (136) so that the coupling member lead (132) can becoupled to the deployment knob (144). FIGS. 9A and 9B show advancementof the catheter (136) and the restrained implant through a vessel (154)toward a desired site. Referring to FIGS. 10A and 10B, once therestrained stent-graft reaches the desired site (156), the deploymentknob (144) is retracted so that the stent-graft progressively expands asshown in the drawings as the coupling member (104) is removed from therestraining member. The coupling member preferably is arranged tofacilitate stent-graft expansion in a direction from the distal toproximal ends of the stentgraft (i.e., in a direction from the cathetertip to the catheter hub). FIGS. 11A and 11B show the stent-graft (106)and restraining member (102) in their final implantation position afterthe coupling member and catheter have been removed therefrom. In anotherembodiment, multiple restraining members may be used as shown in FIG.9C. When the multiple coupling members (104) are released simultaneouslyimplant deployment time may be reduced.

A method for deploying a balloon expandable stent-graft may be the sameas that described above, with the exception that after the couplingmember (104) has been retracted from the eyelets (116), the balloon,which may be positioned inside the stent-graft prior to delivery, isinflated to expand the stent-graft (106) and then deflated for removalthrough the catheter (136).

According to further embodiments of the invention, multidirectionalcoupling member release or multiple coupling members may be used. Theseconfigurations may facilitate more rapid deployment of the implant thanwhen a single unidirectional coupling member is used. FIGS. 12A-12Ddiagrammatically show multidirectional deployment of a restrainedimplant according to the principles of the invention where a couplingmember arrangement is provided to release the implant from its middleportion, preferably its axial center, outward toward the implant ends.Although a particular coupling member configuration is not shown inthese diagrammatic representations, one suitable coupling configurationis shown in FIG. 13 where the leads (132) may be passed through theaperture (152) and coupled to the deployment knob (144) as shown in FIG.9A and described above.

Referring to FIG. 12A, the restrained stent-graft, which is positionedon the distal end portion of delivery catheter (136), is advancedthrough a vessel (154) for deployment in an aneurysm (158). The axialmidpoint of the restraining member (102) preferably is positioned at thecenter of the aneurysmal sac. As the coupling member arrangementunlacing propagates from middle of the construct toward the proximal anddistal ends of the restraining member (102) and the stent-graft (106),the stent-graft (106) progressively expands from its axial midportiontoward its ends as shown in FIGS. 12B and 12C. This may be accomplishedby pulling the leads (132) shown in FIG. 13 simultaneously when thearrangement in that figure is used. The stent-graft size is selected sothat when the restraining member is fully released and the stent-graftfully deployed as shown in FIG. 12D, the proximal and distal portions ofthe stent-graft are positioned against the proximal and distal necks ofthe aneurysm. The delivery catheter may then be retracted.

As is apparent from the drawings, this embodiment advantageously allowsfluid flow through the aneurysmal sac to remain substantiallyunobstructed during the release of the restraining member. For example,the stent-graft ends are still constrained at the deployment time shownin FIG. 12C where the aneurysm neck regions are shown minimallyobstructed. In addition, this simultaneous, multidirectional release ofthe restraining member advantageously reduces the time in which fluidflow in the vessel may disturb the implant position as it is deployed ascompared to a single directional release mechanism such as that shown inFIGS. 9-11.

Referring to FIG. 13, a multiple coupling member configuration is shown.The illustrated arrangement includes two lacing configurations (150) and(152). Except for the placement of the lead (132) of thread-likecoupling member (104), configuration (152) is the mirror image ofconfiguration (150). Accordingly, description of only one of theconfigurations will be made for purposes of simplification. Referring tothe lacing configuration (152), configuration (152) is the same as thatshown in FIGS. 7A-C with the exception that configuration (152) furtherincludes two additional slip knots, generally designated with referencenumeral (504), and tuck or loop arrangement (506). The additional slipknots are not interwoven in the restraining member and provide a delaymechanism for release of the coupling member, as is apparent from thedrawings, when the lead (132) is pulled in the direction of the arrow(134). Thus, inadvertent pulling of the lead (132) will not immediatelybegin to release the coupling member from the restraining member. Thetuck arrangement simply involves tucking the slack from lead (132) understitches at various intervals as shown so that the additional slip knots(504) may be pulled out of the way for delivery. In addition, the tuckor loop arrangement (506) provides an additional delay mechanism forrelease of the slip knots.

As discussed, the delivery systems described above can be used withother implants or devices. These systems, for example, can be used inconjunction with the bifurcated devices described below.

The modular stent-graft of FIGS. 14A through 14D generally has twoprincipal components; a main body (700) and a contralateral leg (730)each generally having a graft member attached to a stent memberaccording to the description above. The main body (700) generally has anumber of sections which have distinct overall constructions. A distaltrunk section (708) has a single lumen structure beginning at a distalend (702) of the main body (700) and continuing until a bifurcationpoint (728). The bifurcation point (728) is the location within theprosthesis where the single lumen of the distal trunk section (708)bifurcates into internal two flow lumen.

An intermediate section (710) begins at the bifurcation point (728) andcontinues to the receiving hole (704). In the intermediate section(710), the stent-graft has an internal graft structure which isbifurcated into two lumen surrounded by a generally tubular,single-lumen stent structure. Finally, a proximal section (712) is asingle lumen structure for both the stent member and the graft memberand includes an ipsolateral leg (726) which terminates at an ipsolateralleg hole (706).

The graft member of the intermediate section (710) bifurcates the singlelumen distal trunk section (708) into the ipsolateral leg (726) and aminternal female receiving lumen (703). The receiving lumen (703)terminates at a receiving hole (704). The receiving hole (704) andreceiving lumen (703) accommodate delivery and attachment of thecontralateral leg component (730). Preferably, the graft material at thedistal end (734) of the contralateral leg component (730) is scallopedas shown more clearly in FIG. 23 discussed below.

The receiving hole (704) is supported by a wire structure around asubstantial portion of its periphery so that the receiving hole (704) isheld open after deployment. In a preferred embodiment the wire structurethat supports the receiving hole (704) is an independent wire ring(714).

The independent wire ring (714) is located in the general area of thereceiving hole (704) in the intermediate section (710). The independentwire ring (714) ensures that the graft material at the receiving hole(704) is supported in an open position to receive the distal end (734)of the contralateral leg (730). In absence of such support, thereceiving hole (704) may not reliably open after delivery of the mainbody component (700) because within the intermediate section (710) thebifurcated graft member in the area of the receiving lumen (703) doesnot have full stent support on its interior periphery. This may bebetter seen in FIG. 18 which shows the absence of any internal stentsupport of the interior graft periphery (785) in the area of thereceiving lumen (703).

The independent wire ring (714) may be comprised of the same materialsas the other stent-graft sections discussed above and is preferablyself-expanding. In a preferred embodiment, the independent wire ringcomprises a single turn of an undulating wire stent material surroundedby at least one layer of tape which is heat bonded to the receiving hole(704). Alternatively, the independent wire ring (714) could be formed asthe last turn of the main body (700).

A radiopaque marker may be used to make the receiving hole (704) visibleduring implantation. Such a marker may include a radiopaque wireadjacent to the independent wire ring (714). Such markers make it easierto see the location of the receiving hole (704) after deployment of themain body (700) within the mammalian body.

This construction of the intermediate stent section (710) as seen incross-section in FIG. 14C is characterized by a single-lumen stentmember and bifurcated graft member and offers both a smaller compressedprofile as well as simplified manufacturing over constructions whichhave discrete stented leg features. The compressed profile is determinedlargely by the physical amount of stent and graft material present in agiven section. This construction eliminates the stent material thatwould normally support the inside periphery of the bifurcated graftsection resulting in less stent material to compress in that region. Asthe main body component (700) is compressed for delivery as discussedabove, the compressed profile is significantly smaller than would be astructure that had a section of bifurcated stent over the section ofbifurcated graft.

Even though bifurcated flow is supported, manufacturing is simplifiedbecause there is no bifurcated stent section. Winding a bifurcated stentsection in one piece, for example, is a more complex process. Likewise,winding separate cylindrical stent structures and connecting them toform a bifurcated stent structure is complicated and ultimately may beless reliable. The intermediate section (710) allows the entire stentmember that covers the main body component (700) to be made from asingle undulating wire arranged in multiple helical turns. The result isa bifurcated stent-graft device which is simple to manufacture, easilycompressible and which expands reliably upon deployment.

An alternate construction of the intermediate stent section (710), isshown in FIG. 14D. The intermediate stent section (710′) has a shapecharacterized by the indented regions (727). The shape could generallybe described as a ‘FIG. 8’, except that the area between the bifurcatedgraft member remains unsupported at its centermost region. Thisconstruction is still a single lumen stent construction and thereforemaintains much of the benefits of reduced profile and simplifiedmanufacturability while providing the bifurcated graft member withincreased support around a greater portion of its perimeter. Further,indented portions (727) have less of a tendency to spring outward uponapplication of external forces.

As mentioned above, the main body component (700) and the contralateralleg component (730) are adapted for delivery in a compressed state to abifurcation site within a body. For this purpose the main body component(700) is preferably equipped with a restraining member (722) constructedas described above. Likewise, the contralateral leg component (730) hasan attached restraining member (732). These restraining members aretypically sutured to the graft material at intervals down their length.

FIG. 15 shows an assembled bifurcated stent-graft (740) after deploymentat a bifurcation site within a bifurcated body vessel afflicted with ananeurysm (758). The prosthesis may be positioned at the location wherethe abdominal aortic artery (752) bifurcates into the left iliac artery(756) and the right iliac artery (754) as shown. So that the variousfeatures of the implant are more clearly shown, the restraining memberis not shown in FIG. 15.

The assembled bifurcated stent-graft (740) is comprised of the main bodycomponent (700) and the contralateral leg component (730). The distalend (734) of the contralateral leg component (730) has been insertedinto the receiving leg hole (704) and the female receiving lumen (703)of the main body component (700).

For best results in deploying any stent or stent-graft of these types itis essential that they have the appropriate structural properties suchas axial stiffness, flexibility and kink-resistance. With complicatedstructures, such as those required for treating a bifurcated site, it isincreasingly difficult to obtain the desired structural propertiesbecause optimizing one may negatively effect the other.

For instance, optimizing the global axial stiffness of a stent orstent-graft will necessarily make the device significantly less flexibleand consequently impair its resistance to kinking and lessen its abilityto conform to the natural bends of curves the body's vasculature.Conversely a device that has high flexibility with little axialstiffness is difficult to properly deploy and does not aid in anchoringthe device in the desired location.

With these constraints in mind, it has been discovered that having abifurcated stent-graft which has segments constructed with varyingstructural properties offers improved deployability, is less susceptibleto kinking, and favorably tends to maintain its desired position afterdeployment while allowing sufficient flexibility to accommodate movementby the body. The exact structural properties desired may depend on thelocation where the prosthesis is to be deployed.

For these reasons, it is preferable that the bifurcated stent orstent-graft be constructed with at least two segments having structuralproperties different from one another. For example, in FIG. 14A, alength of the distal section (708) and the intermediate section (710)may be constructed with a higher axial stiffness for improved deploymentand positional stability while the proximal section (712) may beconstructed to have higher flexibility to accommodate the geometry ofthe iliac artery.

It may be further desirable to have a number of segments that havedifferent structural properties. Accordingly, the main body component(700) and the contralateral leg component (730) of the assembledstent-graft (740) have segments constructed with structural propertiesdifferent from adjacent segments. In one preferred embodiment shown inFIG. 15, the main body component (700) has four different segmentsconstructed with different structural properties. The distal segment(742) is constructed to have higher axial stiffness than the moreflexible proximally adjacent segment (744). The proximal section (748)is constructed to have a higher flexibility than that of its distallyadjacent segment (746). Likewise the contralateral leg component (730)has an axially stiffer distal segment (750) and a more flexible proximalsegment (749).

There are a number of ways to alter the structural properties of stentor stent-graft components. One way of selectively altering thestructural properties of a stent-graft segment is to use a tape memberfor that segment that has different physical dimensions. Such a tapemember is discussed above with reference to the tape member (128) ofFIG. 1. For example the tape member width, thickness or spacing may beincreased, from the preferred dimensions discussed above, in a segmentwhere it is desirable to have increased or decreased stiffness. Forexample, the use of wider tape wound with closer spacing will increasethe stiffness in that area.

Another way of selectively altering the structural properties of a stentor stent-graft segment is shown in FIGS. 14A and 15. Extended struts(718) and (719) may be used to increase the axial stiffness of astent-graft segment. Extended struts are formed by extending an apex onone turn of the undulating wire until it contacts an apex on an adjacentturn. This contact between an extended strut and the apex of an adjacentstent turn provides an added amount of axial stiffness. In a preferredembodiment, a layer of tape (not shown) is applied around the device ina helical pattern that covers each of the apexes of the extended struts.This additional layer of taping keeps the strut pairs together.

Referring to FIG. 14A, a first helical stent turn (720) and a secondhelical stent turn (721) have a generally undulating shape havingapexes. An extended strut (718) of the stent turn (720) is formed havingits apex near or in contact with the apex of the stent turn (721)directly below. The extended strut (719) is similarly formed byextending an apex of the stent turn (721) directly down to contact theapex in the turn below. This pattern in continued, each time spacing theextended strut over one undulation. This results in a helical pattern ofextended struts down the length of the device. Of course, the extendedstruts may be arranged in patterns other than the helical configurationdescribed.

A number of these patterns may be employed in any one segment or theextended strut pattern may be used in other segments to increase axialstiffness. Preferably the distally adjacent segment (746) on the mainbody component (700) and the axially stiff distal segment (750) on thecontralateral leg component are constructed with extended struts asshown.

Referring to FIG. 15, the distal end (702) may be sized to properly fitthe inside diameter of the target artery, in this case the abdominalaortic artery. Typically the prosthesis is designed to have anunconstrained diameter slightly larger than the inside of the targetvessel.

The ipsalateral and contralateral legs of the assembled bifurcatedstent-graft (740) are typically the same size at their distal endsregardless of the size of the distal end (702) and undergo taperedsections (724) and (738) that taper to a diameter which correspondsapproximately to the internal diameter of the iliac arteries. Thesetapered sections (724) and (738) are preferable to abrupt changes indiameter as they tend to produce superior flow dynamics.

After deployment, the assembled bifurcated stent-graft (740) mustestablish sufficient contact with the healthy vessel lumen an each sideof the aneurysm (758) so that the device does not migrate or dislodgewhen subjected to the relatively high fluid pressures and flow ratesencountered in such a major artery, especially when the body againbecomes mobile after recovery. Further, sufficient contact must be madeso that there is no leakage at the distal end (702), the ipsolateral leghole (706) or the proximal end (736) of the contralateral leg.

Anchoring or staying features that allow the stent or stent-graftexterior to anchor itself to the vessel lumen wall may be provided tohelp the device seal to the vessel wall and maintain its deployedposition. For example, anchors (716) as seen in FIGS. 14A and 15 areprovided on the main body component (700) and could also be provided onthe contralateral leg component (730). Preferably the top stent portion(717) is directed angularly outward. This flared stent portion works toforce the anchors (716) into the vessel wall as the top stent portion(717) expands under force into radial interference with the vessel wallupon deployment.

A preferred construction for an anchor (716) is shown in FIG. 17. Thisconstruction involves extending two wires from the upper stent turn(762) under an apex of an adjacent lower stent turn (764). The two endsof stent wires (760 and 761) are then bent out and away from the graftmaterial (768). Extended struts (771) are formed adjacent to each anchorin the manner described above except the extended struts extend underthe adjacent lower stent turn (764) down to a third stent turn (765).This extended strut arrangement provides support for the anchors (716)and provides for low stresses in the wires (760 and 761) under theapplication of bending forces encountered as the prosthesis expands intothe vessel wall. The extended struts (771) minimize the localizeddeformation of the stent-graft structure in the area of the anchors byproviding broader support.

Another construction of the anchors (716′) are shown in FIG. 16. Ananchor (716′) is formed in the same manner except the ends of the anchorremain connected in a ‘U-shape’ configuration as shown. An anchor (716′)may be formed at any location on the stent-graft. Most preferably, theanchors are formed in an evenly spaced pattern around the top stentportion (717) (FIG. 14A).

It should be apparent that the anchors as described above are notlimited in use to the stent-graft combination shown in the figures butindeed could be used in any non-bifurcated or stent only constructionthat require similar functionality.

Sealing at the vessel wall may also be enhanced by the alternateconstruction shown in FIG. 17 by way of a sealing mechanism. A sealingmechanism can be used with any type of implant, including any of theimplants discussed above. For purposes of illustration, the sealingmechanism is shown with reference to the bifurcated implant of FIG. 14and comprises seal member (772) as seen in detail in FIGS. 16 and 17.The sealing mechanism described below can be used with any of theimplants discussed above.

One preferred construction for seal member (772) in the variations shownin FIGS. 16 and 17 may be similar to the preferred construction for thetape member used in constructing the stent-graft tubular member, as isprovided in reference to FIG. 1A and FIG. 3 above.

In general, a thin walled ePTFE tape is used for seal member (722)similarly as that for tape member (128), shown variously in the previousfigures. The tape used for seal member (722) is adhered to the outersurface of the stent-graft, including over tape member (128), describedpreviously for bonding the stent and graft members. Seal member (722)has an inner surface constructed of a similar material for either theouter surface of the tape member (128) or the outer surface of thegraft-member (124), depending upon which surface the seal member isdesirably adhered.

First cuff end (767) is bonded to the stent-graft outer surface andsecond cuff end (769) is not, in order to form the unadhered flange tofunction as a one-way valve against peri-stent-graft flow. Seal member(722) may be selectively adhered along its length in this manner byproviding a variable inner surface to the seal member such that, uponheating, only the surface in the region of first cuff end (767) bonds tothe outer surface of the stent-graft. For example, the inner surface ofseal member (722) may have an FEP liner in the region of first cuff end(767) but not in the region of second cuff end (769). In this case, uponcontacting an outer surface of the stent-graft that has a uniform FEPouter surface, only first cuff end (767) may be heat secured thereon.

Alternatively, seal member (722) may have a uniform inner surface, suchas constructed of FEP, and a variable outer surface, such as with aselective portion of FEP, may be provided either on the tape member(128) or on the graft member (124) in the region where the heat bondingof seal member (722) is desired. Still further, seal member (722) mayhave a uniform surface and may be positioned over tape member (128) andgraft member (124) so that variability between the outer surfaces oftape member (128) and graft member (124) causes a selective bonding withthe first cuff end (767) over one of those surfaces.

Further to the construction of seal member (722), the particular wall ofthickness of the tape which may be used for this component shoulddesirably be as thin as possible to functionally provide theflange-one-way-valve function for that member. This is because, sinceseal member (722) is over the outer surface of the other stent and graftcomponents of the stent-graft, seal member (722) is believed to be theprofile-limiting feature of the overall assembly. Therefore, in aparticular design, seal member (722) may desirably be a thinner wallthan for the tape member used to construct the stent-graft described inreference to FIGS. 1 and 3.

Further referring to the particular constructions and related methodsjust described for adhering seal member (722) to the outer surface ofthe underlying stent-graft, it should be apparent to one of ordinaryskill in the art that the desired construction and heat securingtechnique for seal member (722) is premised upon the theory that, whereone polymer meets a like polymer (such as FEP meeting FEP), heatingunder proper conditions will allow for a selected heat bond. Anysuitable means may be used for securing a seal member to the outersurface of a given tubular member, as would be apparent to one ofordinary skill.

Further there is a plurality of circumferential strut spaces between thestruts of the stent member. It is believed that these spaces may providea path for leakage flow around the outer surface of the graft member andalong the outside of the stent-graft. Second cuff end (769), however,captures such leakage flow beneath its flange, which can not propagatealong the outer surface of the stent-graft because first cuff end (767)is secured to the outer surface of that stent-graft. In other words,flow over the stent-graft and into an aneurysm is occluded.

Furthermore, when apex strut (716) is anchored into the wall ofabdominal aortic artery as shown in FIG. 15, it has been observed thatthe portion of main body component (700) at and adjacent to the apexstrut (716) may be forced away from the artery wall. This action causesa separation between the outer surface of main body (700) and the arterywall, which separation is believed to create a leakage flow path. Theflange of seal member (772) captures that flow and occludes it frompropagating into the aneurysm (758).

In addition to maintaining a good contact with the vessel lumen walls,the components of the stent-graft must make sufficient contact with eachother such that the separate modules stay attached and do not leak attheir engagement interface. The stent-graft shown in FIG. 18 illustratesseveral important features designed to effectuate a leak-free andpositionally stable seal at the interface between the receiving lumen(703) of the main body component (700) and contralateral leg component(730).

FIG. 18 shows a partial cross-section of the assembled stent-graft. Thecontralateral leg component (730) has been inserted into the receivinglumen (703) of the main body component (700). This cross-sectional viewshows clearly that the main body component (700) includes a main bodygraft member (780) and a main body stent member (782). The contralateralleg component (730) includes a contralateral graft member (784) and acontralateral stent member (786).

At the interface between the contralateral leg component (730) and thereceiving lumen (703), the assembly provides for an extending sealingregion (790). Preferably the extended sealing region (790) consists of agenerally cylindrical interfering friction fit between the outsidediameter of the contralateral leg component (730) and the insidediameter of the receiving lumen (703). That is, the natural or restingoutside diameter of the self expanding contralateral leg component (730)would be larger than the natural inside diameter of the receiving lumen(703). Thus the forces created by the interference act to seal the twocomponents and also serve to resist movement of the two components.

The type of generally cylindrical extended sealing region just describedhas many advantages. First, it allows for the stent and graft structuresin the extended sealing region (790) to be constructed of relativelysimple generally cylindrical elements that are easily manufactured.Because the extended scaling region (790) extends over a large length itnecessarily has a large surface area to effectuate sealing between thecomponents. This larger sealing area typically provides that multipleturns of the stent structures will be engaged in an interfering and thussealing relationship.

In one preferred embodiment, the extended sealing region has a length inexcess of one-half of the diameter of the receiving lumen (703), morepreferably the length is greater that the diameter of the receivinglumen (703), and most preferably the length is more than 2 times thediameter of the receiving lumen (703).

Because the manufacturing tolerances of the simplified shapes are easilycontrolled and because the engagement of the extended sealing region(790) is quite large, a highly reliable joint is formed between themodular components. Even so it may be desirable to create one or morelocalized zones of increased interference to increase the sealingcapability and positional stability.

Localized zones of interference may be created in a number of ways. In apreferred embodiment, an annular ring of decreased diameter is formedwithin the receiving lumen. Such a localized decreased diameter causes agreater interference with the outside diameter of the contralateral legcomponent in a localized area while the remainder of the engagement withthe receiving lumen is subject to the general interference friction fitdescribed above.

One way of creating a localized decreased diameter is illustrated inFIG. 20 which shows a partial cross-section of the extended scalingregion (790). A zone of reduced diameter (799) is created by placing ananchoring ring (798) between the graft member (780) and the stent member(782) of the receiving lumen (703). The anchoring ring may be made fromany polymeric or wire material, preferably a material that will notinhibit the receiving lumen from self-expanding to an open position.Most preferably the material is a suture material, typically ePTFE.

Alternately, localized zones of decreased diameter may be created asshown in FIGS. 21 and 22 by folding a portion of the graft member (780)back up into the receiving lumen (703). In FIG. 21, the zone of reduceddiameter (806) is formed by creating a folded flap (808) of the graftmaterial (780) around an anchoring ring (802). The flap is heat bondedin place roughly at a location (804) as shown. In FIG. 22, the zone ofreduced diameter (809) is formed of flap (808) and heat bonded roughlyat a location (807) in a similar manner but without any anchoring ring.The localized interference using these methods tends to cover a largerarea and the flap (808) provides a more flexible member to seal againstthe outside diameter of the contralateral leg component (730).

One further aspect of ensuring a good seal between the stent-graftcomponents involves the use of a scalloped stent-graft construction atthe distal end of the contralateral leg component (810). To create thisscalloped construction, the graft material between the apexes of thestent member is removed on the last turn of the stent. For examplescallop (812) may be formed by removing (or cutting and folding under)the graft material from between a first apex (814) and an adjacent apex(816).

The advantages of using a scalloped arrangement are illustrated in FIGS.24A through 25B. FIG. 24A shows a cross-section of the fully expandedcontralateral leg component (730) having an unscalloped construction. Afirst apex (822) and an adjacent apex (824) have continuous graftmaterial (784) in the area between them. When the apex (822) and theadjacent apex (824) are forced together in the directions of the arrows(820), the graft material (784) forms a buckle or wrinkle (818) which isa potential leak path or is a potential site for thrombogenic materialto build up as seen in FIG. 24B. The scalloped construction shown inFIGS. 25A and 25B, on the other hand, have no graft material between thefirst apex (814) and the adjacent apex (816) and therefore when forcedtogether do not form a graft material wrinkle.

The wrinkle (818), mentioned above may also be formed when thestent-graft is not allowed to expand to its complete diameter. Forinstance it is quite common that the receiving lumen or vessel wallinternal diameter is smaller than the fully expanded stent-graft outerdiameter. This being the case, it should be clear that the scallopedconstruction may alternately be used at any of the terminal openings ofthe main body component or the contralateral leg component. Preferably,the distal end (702) of the main body component (700) also has thisscalloped construction as shown in FIGS. 14A and 14B.

In the previous discussion we have referred generally to a stent-graftthat includes a graft member. While the construction of such straightstent grafts are discussed at length above, the construction of abifurcated graft member is illustrated in FIGS. 26, 27A and 27B. Abifurcated graft member suitable for construction of the main bodycomponent (700) discussed above is generally formed of two graftmembers: the ipsolateral tapered graft (840) and the contralateraltapered graft (842). The separate contralateral leg graft component(844) is a straight or tapered section and may be formed according tothe principles discussed in the first section above.

The ipsilateral tapered graft (840) has three sections which areseparated by tapers. A top section (846), a middle section (848), and abottom section (850). The body component graft (854) is formed by heatbonding the top section (846) of ipsolateral tapered graft (840) to thetop section (847) of contralateral tapered graft (842). This heatbonding forms a common septum (856) which in a preferred embodiment issubsequently cut away to produce a smooth bifurcation (858). Cuttingaway the septum material prevents fluid flow disturbance or blockagethat could result from deviation of the septum. Such deviation is causedby the fluid pressure and is aggravated if the stent-graft is radiallycompressed in a manner which causes the septum to become loose or nolonger taut.

In another embodiment, a graft section may be constructed in the mannerillustrated in FIGS. 27A and 27B. According to this embodiment, the bodycomponent graft (867) is constructed from two pieces. A tubular graftsection (860) is bent into a ‘U-shape’. A top hole (864) is formed bynotching the top of the ‘U-shape’. Upper graft section (862) is placedover the top hole (864) of tubular graft section (860). The two piecesare bonded together at the bonding interface (866). Preferably, the twograft pieces are heat bonded while supported by interior mandrels (notshown) to obtain the desired shape and smooth interior. However, uppergraft section (862) may be attached to the tubular graft section (860)at the bond interface (866) in any manner that provides a sufficientlyleak free seal. For example the components may be sutured together oradhesive bonded.

In use, the modular bifurcated stent-graft is typically deliveredpercutaneously through the vasculature of the body. Preferably theprosthesis is delivered by way of a restraining member as described indetail above. FIGS. 28A through 28E diagrammatically illustratedeployment of a bifurcated stent-graft with a restraining member (902)using a percutaneous catheter assembly. Referring to FIG. 28A, amultilumen catheter assembly (928) has been inserted to a selected sitewithin a body lumen. The main body component (700) of a bifurcatedstent-graft is held in a compressed state about a guidewire (926) and aguidewire lumen (929) by a restraining member (902) and a couplingmember (906). The collapsed main body component (700) is held axially inplace prior to deployment by a distal barrier (930) and a proximalbarrier (932). The distal (930) and proximal (932) barriers aretypically affixed to the guidewire lumen (929). The coupling member(906) extends through the eyelets (920) of the restraining member (902)forming chain knots and into the multilumen catheter (928).

FIG. 28A shows advancement of the multilumen catheter (928) with thedistally located main body component (700) and the restraining member(902) into implantation position, typically at the bifurcation of amajor vessel. During deployment it is critical that the surgeon alignthe main body component (700) so that the ipsolateral leg (726) willextend down one branch of the bifurcated vessel, and so the receivinghole (704) and the receiving lumen (703) will be lined up with the otherbranch of the bifurcated vessel so as to receive the contralateral legcomponent (730).

One way of facilitating this alignment is to provide radiopaque markersso that the surgeon may readily determine the rotational position of themain body component (700) prior to deployment or release from therestraining member (902). In a preferred embodiment, a long marker (934)is located on the contralateral side of the compressed assembly and ashorter marker (936) is placed on the ipsolateral side. Preferably thesemarkers are placed on the stent prior to compression but mayalternatively be part of the restraining member. Having one marker of adifferent length allows the surgeon to identify the orientation of boththe ipsolateral leg and the receiving lumen relative to the bifurcatedvessel.

Once the assembly is properly aligned and positioned for implantation,the coupling member (906) is pulled and the restraining member (902)begins to release the implant, typically at the distal end first. In thepreferred embodiment, the restraining member (902) is located down theside as shown because it is less likely to interfere with deployment ofthe receiving lumen (703).

FIG. 28B shows the main body component (700) radially expanding as thecoupling member (906) is retracted through the eyelets (920) of therestraining member (902) and into the catheter assembly (928). In thepreferred embodiment, the restraining member (902) has been fixedlyattached to the main body component (700) with a number of sutures alongthe length of the main body component to prevent any relativelongitudinal movement between the implanted prosthesis and therestraining member (902). The restraining member may optionally employ aretracting or pull-down mechanism as described at length above.

FIG. 28C shows the main body component (700) and the restraining member(902) in final implantation position at the vessel bifurcation after theguidewire (926) and the catheter assembly (928) have been retracted.

FIG. 28D shows the contralateral leg component (730) being delivered tothe contralateral receiving hole using a restraining member (942). Theprocedure for positioning and releasing the contralateral leg component(730) is the same as that described above for implantation of agenerally cylindrical stent-graft except that certain radiopaque markersmay be employed to ensure its proper position relative to thebifurcation point (728) of main body component (700).

Radiopaque markers may be located, for example, to indicate the positionof the receiving hole (704), the distal end (734) of the contralateralleg component (730), and the bifurcation point (728) of the main bodycomponent (700). These markers serve to indicate the position of thecontralateral leg component as it enters the receiving hole (704) andits ultimate position relative to the receiving lumen (703) which beginsat bifurcation point (728). In a preferred embodiment illustrated inFIG. 19, the radiopaque wires (794) may be heat bonded or imbedded intothe graft material (780) around the periphery of the receiving lumen.Such radiopaque wires could be used in other places such as thecontralateral leg component lumen, the ipsolateral leg lumen or thelumen at the distal end of the main body component (700).

FIG. 28E shows the assembled bifurcated stent-graft in its finalimplantation state with the contralateral leg component expanded intoand engaged with the receiving lumen of the main body component (700).

FIGS. 29A through 29D diagrammatically show the same stent orstent-graft components being deployed except that the restraining member(902) is released from the center out towards as the coupling member(906) is retracted. This may provide more accurate placement relative tothe bifurcation point of the vessel instead of relative to the distalend as with end release.

While this invention has been described with reference to illustrativeembodiments, this description is not intended to be construed in alimiting sense. Various modifications and combinations of theillustrative embodiments, as well as other embodiments of the inventionwill be apparent to persons skilled in the art upon reference to thedescription. It is therefore intended that the appended claims encompassany such modifications or embodiments.

The disclosures of the publications and patents that are cited in thisapplication are hereby incorporated by reference.

1. An endoluminal implant device for implanting within a body lumenhaving a natural lumen diameter, the device comprising: a tubular graftmember made of expanded polytetrafluoroethylene, wherein the graftmember has a proximal end for positioning in an upstream location of thebody lumen and a distal end for positioning in a downstream location ofthe body lumen; a stent member attached to the proximal end of the graftmember, wherein the stent member is self-expanding from a collapsedconfiguration to an expanded configuration, wherein a diameter of thestent member in the expanded configuration is larger than the naturallumen diameter of the body lumen, and wherein the stent membercomprises: a wire undulating around the graft member, the undulatingwire defining proximal apexes and distal apexes, and a plurality ofanchors disposed around the undulating wire, wherein each anchorprotrudes from the wire away from the graft member and in a directiontoward the distal apexes, and is disposed between the proximal apexesand the distal apexes along the longitudinal axis of the graft member.2. The device of claim 1, wherein the each anchor comprises a wirehaving an open end bent out and away from the graft member.
 3. Thedevice of claim 1, wherein the each anchor comprises two wires havingopen ends bent out and away from the graft member.
 4. The device ofclaim 1, wherein the each anchor comprises a U-shaped wire.
 5. Thedevice of claim 1, wherein the anchors of the plurality of anchors aredisposed in an evenly spaced pattern around the circumference of thegraft member.
 6. The device of claim 1, wherein the proximal apexes ofthe undulating wire project angularly outward from the remainingportions of the undulating wire and from the longitudinal axis of thegraft member.
 7. The device of claim 1, wherein the graft membercomprises an inside face and an outside face, wherein the stent memberis disposed over the outside face of the graft member, and wherein thedevice further comprises a tape member disposed over the stent member,the tape member bonded to the graft member through openings in theundulating wire of the stent member.
 8. The device of claim 7, whereinthe tape member comprises fluorinated ethylene-propylene coated expandedpolytetrafluoroethylene.
 9. The device of claim 1, wherein the wireundulates around the graft member in a helical pattern.
 10. The deviceof claim 1, wherein the wire undulates around the graft member in asingle turn to form a ring.
 11. The device of claim 1, wherein theundulating wire comprises an upstream turn and a downstream turn aroundthe graft member, and wherein the each anchor extends from the upstreamturn and under a proximal apex of the downstream turn, and protrudesaway from the graft member downstream of the proximal apex.
 12. Thedevice of claim 11, wherein the upstream turn comprises extended strutsformed adjacent to each anchor and extending under the downstream turn.13. The device of claim 1, further comprising a restraining member inwhich the device is constrained in a collapsed state for deploymentwithin the body lumen.
 14. The device of claim 13, wherein therestraining member comprises a pull line that releases the restrainingmember to allow the device to expand.
 15. The device of claim 1, whereinthe stent member has an expansion ratio of approximately 5:1.
 16. Thedevice of claim 1, wherein the each anchor extends from a proximal apexof the undulating wire.
 17. The device of claim 1, further comprising anouter graft member made of expanded polytetrafluoroethylene, wherein thestent member is sandwiched between the tubular graft member and theouter graft member to attach the stent member to the proximal end of thetubular graft member.
 18. An endoluminal implant device for implantingwithin a body lumen having a natural lumen diameter, the devicecomprising: a tubular graft member made of expandedpolytetrafluoroethylene, wherein the graft member has a proximal end forpositioning in an upstream location of the body lumen and a distal endfor positioning in a downstream location of the body lumen; a stent wireattached to the proximal end of the graft member, wherein the stent wireundulates around the graft member and defines proximal apexes and distalapexes, wherein the stent wire is self-expanding from a collapsedconfiguration to an expanded configuration, and wherein a diameter ofthe stent wire in the expanded configuration is larger than the naturallumen diameter of the body lumen; and a plurality of anchor wiresdisposed around the undulating stent wire, wherein each anchor wireprotrudes away from the graft member at a location between the proximalapexes and the distal apexes along the longitudinal axis of the graftmember, and in a direction toward the distal apexes.
 19. The device ofclaim 18, wherein the each anchor wire is attached to a proximal apex ofthe undulating stent wire.
 20. The device of claim 18, wherein the eachanchor wire extends from a proximal apex of the undulating stent wire.21. The device of claim 18, wherein the each anchor wire is an integralportion of the undulating stent wire.
 22. The device of claim 18,wherein the each anchor wire comprises two open ends bent out and awayfrom the graft member.
 23. The device of claim 18, wherein in anexpanded configuration, a diameter of the undulating wire at theproximal ends is larger than a diameter of the undulating wire at thedistal ends.
 24. A method for manufacturing an endoluminal implantdevice for implanting within a body lumen having a natural lumendiameter, the method comprising: forming a tubular graft member fromexpanded polytetrafluoroethylene, wherein the graft member has aproximal end for positioning in an upstream location of the body lumenand a distal end for positioning in a downstream location of the bodylumen; forming a stent wire that wraps in a generally cylindricalconfiguration to define an interior area and an exterior area, andundulates to define proximal apexes, distal apexes, and openings betweenthe distal and proximal apexes, wherein the stent wire is self-expandingfrom a collapsed configuration to an expanded configuration, and whereina diameter of the stent wire in the expanded configuration is largerthan the natural lumen diameter of the body lumen; forming a pluralityof anchor wires disposed around the undulating stent wire, wherein eachanchor wire protrudes away from the interior area at a location betweenthe proximal apexes and the distal apexes along the longitudinal axisdefined by the cylindrical configuration, and in a direction toward thedistal apexes; placing the tubular graft member on a mandrel; placingthe stent wire over the tubular graft member; placing an outer graftmember, made from expanded polytetrafluoroethylene, around the stentwire such that the outer graft member is exposed to the tubular graftmember through the openings in the stent wire; heating the outer graftmember and the tubular graft member to adhere the outer graft member tothe tubular graft member through the openings in the stent wire, therebyforming the implant device; and removing the mandrel from inside thetubular graft member.
 25. The method of claim 24, further comprisingcollapsing the implant device; placing the collapsed implant deviceinside a restraining member that constrains the implant device in acollapsed state; and attaching a coupling member to the restrainingmember, wherein the coupling member is configured to release thecollapsed implant device from the restraining member to allow theimplant device to expand to an expanded state.
 26. An endoluminalimplant device for implanting within a body lumen having a natural lumendiameter, the device comprising: a tubular graft member made of expandedpolytetrafluoroethylene, wherein the tubular graft member has a proximalend for positioning in an upstream location of the body lumen and adistal end for positioning in a downstream location of the body lumen; astent member attached to the proximal end of the tubular graft member,wherein the stent member wraps in a generally cylindrical configurationaround the tubular graft member, wherein the stent member isself-expanding from a collapsed configuration to an expandedconfiguration, and wherein a diameter of the stent member in theexpanded configuration is larger than the natural lumen diameter of thebody lumen; and a plurality of anchors attached to the stent member,wherein each anchor protrudes away from the tubular graft member and ina direction toward the distal end of the tubular graft member.
 27. Thedevice of claim 26, further comprising an outer graft member made ofexpanded polytetrafluoroethylene, wherein the stent member is sandwichedbetween the tubular graft member and the outer graft member, and whereinthe outer graft member and the tubular graft member are attached to eachother through openings in the stent member, to attach the stent memberto the proximal end of the tubular graft member.